redirection problem

Hi, I have been having some problems with redirection. My wordpress files are in mydomain.com/blog folder and I have been using the blog adress also as mydomain.com/blog, but now I want to move the address to the root, just mydomain.com/ however even tough I change the “Blog address (URL): mydomain.com/” when I enter an address like “mydomain.com/blog/category/test” this address is not directed to “mydomain.com/category/test” and throws a 404 error.

I have copied index.php and .htaccess from blog folder to the root as it says in http://codex.wordpress.org/Giving_WordPress_Its_Own_Directory
And my .htaccess is like the following:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>

# END WordPress

RewriteCond %{HTTP_HOST} ^blog.buyruk.net$ [OR]
RewriteCond %{HTTP_HOST} ^www.blog.buyruk.net$
RewriteRule ^(.*)$ http://buyruk.net [R=301,L]

How can I solve this problem?